Multiple-hammer-piston rock-drilling engine.



PATENTED FEB. 5, 1907.

J. G. LEYNER. MULTIPLE HAMMER PIS'ION ROCK DRILLING ENGINE.

APPLICATION FILED MAY 9,1905.

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E M16/eds wwf au No. 843,1b). PATEN'TED FEB. 5, 1907. J.v G. LBYNBR. MULTIPLE HAMMER PISTON ROCK`DRILLING ENGTNE. APPLICATION FILED MAY 9.1905.

4 SHEETS-SHEET 2.

,//////////////////N mw/ Q No. 843,159. PATENTED EEB. 5, 1907. J. G. LEYNEE. MULTIPLE HAMMER 'PISTON ROCK DEILLING ENGINE.

AAAAAAAAAAAAAAAAAA Y 9,1905.

V um fi l fl I1 gl I Y -'E E D N) W-.. M J7 muy w E 7 No. 843,159. PATENTED PEB. 5, 1907. J. G. LBYNER. MULTIPLE HAMMER PISTON ROCK DRILLING ENGINE.

APPLICATION I'ILED MAY 9,1905.

4 SHEETS-SHEET 4.

, construction of rock-drilling engine these objects and certain other advantageous UNITED STATES PATENT OFFICE.

MULTIPLE-HAMMER-PISTON ROCK-DRILLING ENGINE.

Specification of Letters Patent.

Patented Feb. 5, 1907.

Application filed May. 1905. Serial No. 259.618.

To all, whom llt/ may canoe-rn:

Be it known that I, JOHN GEORGE LEY- NER, a citizen of the United States of America, residing at the city and county of Denver and State of Colorado, have invented anew and useful Multi le-Hammer-Piston Rock-Drilling Engine, o which the following is a specification.

My invention relates to improvements in rock-drilling eILgI-rines; and the objects of my invention are, st, to provide an improved aving a pair of reciprocatory hammers arran ed to strike alternate blows u' on the drillit or upon an interposed stri 'ng-pin; second, to provide an implroved construction of rockdrilling engine aving a pair of hammer-pistons actuated by fluid motive ower, each acting as the valve for the ot er and arranged to reciprocate in cylinders the axes of which are at an acute angle to each other, so as to deliver alternate blows to the drillbit. .The construction by which I attain results will now be described in detail in connection with the accompanying drawin s,` in whichigure- 1 is a plan view of the improved multiple hammerpiston rock drilling engine detached from its sup' orting-shell. ig. 2 is a horizontal longitu inal sectional view thereof. Fig. 3 is al vertical longitudinal sectionalview thereof on the line 3 3 of Fig. 1. Fig. 4 is a side elevation of the rockdrilling engine, the Vsupporting-shell being shown in section. Fig. 5 is a vertical lon tudinal .sectional view through one of t e lhammer-piston` cylinders on the line 5 5 of Fig. Fig. 6 is a transverse sectional view on the line 6 6 of Fig. 1. Fig. 7 is a transverse sectional View on the line 7 7 of Fig. 1. Fig. 8 is a transverse sectional view on the line 8 8 of Fig.`1. Fig. 9 is a transverse sectional view on theline 9 9 of Fig. 1. is a transverse sectional view on line. 10 1() of Fig. 1 looking in the direction of the arrow; Fig. 11 is a front elevation thereof, the front cylinder-head, dr'ill, rotating gears, and hammer-pistons being removed.' Fig. 12 is a front elevation of the drilling-engine, the front cylinder-head beingomitted. Fig 13 is a perspective view of the drill-bit used in connection rwith this drilling-engine. Fig. 14 is a fragmentary plan view of a rock-drilling engine, showing my multiple-hammer pistons arranged to strike directly on .the end mer-pistons.

Fig. 10

that separates the two cylinders.

of a rock-cutting drill-bit,which is supported loosely and revolubly in the drilling-engine in a suitable chuck. the striking-plm and buffer devices of the arrangement s own in Figs. 2 and 3 are dispensed with, and the drill-holding chuck acts as a buffer for the spent blows ofthe hamis a rear view of the upper half vof said cylinder-head.

Fig. v15 is a vertical sectionalv 4view of the front cylinder-head, and Fig. 16

1n this arrangement Similar letters of reference referto similar parts throughout the several views.'

Referring to the drawings, the numeral 1 designates a casing,l referably a casting, in which at its front end) is formed, and at its rear end two cylinders 4 and 5 are formed, which are preferably arranged in a horizontal plane side by side. These two cylinders extend rearward from the front central cylindrical bore 3 at a slight diverging angle onopposite sides of the axial center line 3 3 ofthe front central cylindrical bore 3, and they are also arranged to intersect or converge into each other and into the front central cylindrical bore, preferably with the greater portion of their diameters. These c linders 4 and 5 are also arranged at an angle relative to each other and to the front cyof their forward ends to intersect each other at about the inner terminal end of thefront central cylindrical bore 3, and the partition 6- 2 a cylindrical bore 3 .85 lindrical bore that brings the adjacent sides large chamber 7^ at their intersecting oints.

The two angular cylinders are pre erably made in two diameters, the larger diameter being at their rear ends. The larger bore of each cylinder is preferably made a little longer than the smaller bore. The chamber 7"* at the forward end portion of the smaller bore of each cylinder forms a large circumferential exhaust-port, one ywall of which is preferably formed at the end of the partition From this wall this exhaust-port extends forward a vshort distance, its width being sufficient to IOO allow variations of the length of the stroke-of the hammerrelative to the end of the drillbit, as win be explained fuuy hereinafter,

From this exhaust-port an exhaust-aperture .together at shoulders -11A and-12,

9 vextends -throu h the shell, preferably at its bottom, cent1'V y between the cylinders to the atmosphere. In these two angular cylinders'I Afit hammer-pistonsll and 12, each of which is made in'V two diameters that meet These two pistons are adapted to fit the two circumferential bores of 4each cylinder.- Both of these angular-arranged. c linders and both- `hammer-pistons are of.t e same size and le th. These two pistons are provided axial ports 1-1B and 12B, that extend into their rear ends to near their front ends, from which radial ports lland 12C extend through the shells of the-hammers. The rear ends of these two circular c linders are -interiorly threaded, and a nut-s aped plugcylinder head 1.3 is threaded to each. These nut-shaped plug-cylinder heads are provided A with a chamber'v 14, that extends into them A"tion 17 is formed on the casing over-the cylinder 4 and forms an integral part of the hub 1,6, and f onthe casing a cross-lug 17A is alsb formed, that connects with and extends rea ardly from the lug 17 at an angle toward the cylinder 5. Y

The motive-fluid inlet-aperture 15 is intelriorly threaded to receive a hose connection.

vThe aperture 15 extends'intov the hub only a short distance, and an inlet-port -18 is drilled at an angle through the hub and casing into vcircumferential ports. 19 and 20, that are formed in both cylinders a short distance to the rear of the shoulders 21 and 22, that are formed in the cylinder at the intersection of its two' diameters and which consist of circumferential ooves in the periphery of the cylinders'r Trese ports are connected together by an aperture 22A, that 4is formed through the partition 6. From the 'bottom of the inlet-aperture 15 two inlet-ports are formed, which I' will designate A and B.A The inlet-port A connects, through the cylin'-= drical bore 4, with a port A', which isdrilled down through Athe lug 17 into the cylinder 4, the entrance to which is threaded and plugged by a threaded plug 20.' (See F 7.) port A registers with a 'port A2', that is drilled through the lug 17 A from its end to intersect the port A. The outer end of the port-A2 is plugged up.- This port A2 intersects a port A3, that is'drilled down through a'boss 17B,that is formed on the end of the lug 17". This port A3 is drilled at an angle The that'will bring it out into the cylinder 5 near its rear end. The port B connects, through the cylinder 5, with the port B', (see Fig. 7,) whichisv intersected by a tween the two cylinders until it intersects a port B2, that is drilled longitudinally through the shell be; 47c

port B3, which enters the rear end of the cyl- K inder 4 in, the same position asthe port Aa enters the cylinder V5. `The ports A and B, however, do not register opposite each other,

the port A being placed a trifle forward of the Aport B toward the front end of the cylinders,

the object of this arrangement being to prevent the centering or locking of both pistons, so-that they will e sure to start in any position relativelto each other they may assume. Thus if the drill was turned vertically upward, so thatthe hammer-pistons both dropped to the 'rear end of, their cylinders and were not in operation, the inlet-port B would be covered up by the largest diameter `.portion of the hammer-piston 12 as the forward edge 12* would Aextend over it. The

port A, however, is laced forward of the port B sufficient to enab e a ortion of it to extend over the edge 11,A of t e hammer-piston 11 and be open to the space surrounding; the smaller diameter of the hammer-piston 11. This arrangement of the port- A permits the motive fluid to How from the port A around the smaller part of the hammer-pistonv 11 into port A and through cross-port A2 into and through ort A3 into the rear end of the cylinder 5, w ich starts the hammer-piston 12 forward, and, driving its forward stroke, it acts as a valve to start the hammer-piston 11, as will befully explained hereinafter. Ifboth hammer-pistons were at. the forward Vend of the drill, as-would be the case if the drill was inclined downward and was inopertive, and the striking-pin also dropped down in the buffer-sleeve 25A so that ,the ham-` mer-pistons rested against the end of the steel buffer-sleeve, they would be far enough forward to bring the edges of 'their shoulders 11A and 12A past the ports 21 and 22, respec- AIIO tively, and they would notstart back quickl but might start slowly from the forward lea age of the motive fluid; but the 'instant the drill-bit was fed forward by the feed-screw against rock it would raise the striking-pin against the hammers, and't-h'eir shoulders 1 1f* and 12A would be moved -back past these ports into .their normal operative positions and would immediately start on their rear- Ward lstrokc, and. the hammer-piston 12 would'be started forward first, as it would receive the motive fluid fromthe inlet-portA,

as above described, and the hammer-pistons would immediately start to reciprocate in opposite directions in successive 'alternate order.' These two ports register with two circumferential ports 22B and 23, formed inv the hammer-pistons 11 and 12, respectively, adjacent to their rear ends and positioned to i register with said ports A and B when the 'two cylinders through the medium of the two pistons, which reciprocate in opposite directions simultaneously and in the following manner: Assuming that the pistons 11 and 12 are in the positions shown in Fig. 2, the motive fluid enters'the port A and flows around the circumferential port 22B into 'the port A', from which it flowsintothe crossoverort A2 into the port A3 and .into the cylin er 5 at the rear end of the hammer-piston 12, which has not quite reached the -end of its rearward stroke, but is in the same relative position as the hammer-piston 11, which has not quite reached the end of its forward stroke. Consequently the motive fluid, which may be compressed air, flows in behind the hammer-plston 1,2 and cushions its rearward stroke and starts it forward .at the same time the piston-hammer 11, which is at the forward end ofits stroke and which has struck its blow, has its exhaust-ports 11C registering with the exhaust-chamber 7 A and the air that drove it forward has escaped through the exhaust-aperture 9 to the atmosphere and the pressure fis removed from its rear end, and a portion of the air flowing into the inlet-aperture 15 fiows through the ports 18 and 19 to the front of the shoulder 11a of the piston 11, and it is moved rearward and closes the air-inlet port A as it passes over it. 'Consequently the hammerpiston is moved rearward by the air' flowing to the front f its shoulder 1 1^, and it actsas a valve tob admit and control the forwardstriking movement of the hammer 12. In the same manner the hammer-piston 12 acts asa valve for the hammer-piston 11, as when the hammer-piston 12 is at the forward end of its stroke the air behind it is exhausted through its axial port 12B and out of its radial' exhaust-ports and through the exhaust port and aperture to the atmosphere. The air then enters the port B and flows through the ports BA and B2 and B3 into the rearward end of the cylinder 4 and starts the hammerpiston 11 forward, while the air entering'the ports 18 and 20 to the front of the lshoulder driving the drill-bit, and preferably arrange it as follows: In the front cylindrical bore of the casing I place a buffer-sleeve 25A, which fits loosely and slidably in the bore and extends a short distance from the rear end of the cylindrical bore in which it rests into and slightly beyond the end of the chamber formed by the intersection of the two angularly-disposed cylinders and against shoulders 25B at the junction of t-hese three cylinder s, that permits the sleeve to project into the reciprocal ath of the two pistons. These shoulders are ormed b the contour of theV exhaust-chamber, whic is in the shape of the ligure 8, the vwall between thetwo portions of the chamber being cut away centrally where the chambers intersect. (See Fig. 9.) The buffer-sleeve 25A is provided with an axial bore of two diameters 25C and 26, the smallest of which extends into it from its hammer-striking end. This bore 25C extends into the buffer-sleeve but a short disi tance, and it is intersected by the larger bore 26, which extends into thev sleeve from its rear end the greater portion of its length and intersects the smaller bore 25C witha square shoulder 27. Thisbuffer-sleeve occupies a portion of the front cylindrical bore 3. At.

its front end a steel buEer-ring 28, that fits snugly but loosely in the cylinder, is placed, which is providedwith a thin hub portion 29, that extends into the larger bore 26 vof the steel buffer-sleeve a portion of its length,

thus leaving a space between the end of the sleeve and the square shoulder 27. This steel ring I term a. buffer-hub ring.

Against the front side of this steel ring a rubber buffer-ring 30is placed in the cylinder 3, and against the rubber ring a steel washer 31 is placed, which also fits snugly the cylin- ICO IIO

the rock-cutting drill-bit 33, and which I terma drill-bit-holdin chuck. The inner end of this drill-bit-hol ing chuck fits loosely and rotatably in the axial apertures of these buffers and the washer and extends within the steel buffer-sleeve to close to the inner end o f the steel buffer hub-ring 29.' Within the steel buffer-sleeve and the inner end of the 'drill-bit-holding chuck I fit loosely and-slid'- ably the striking-pin 25, which preferably consists of a short slu or stud member, the striking end of which ts loosely` in the small axial bore of the steel buffer-sleeve and normally projects beyond the steel buffer-sleeve intothe reciprocating path of the two pistonhammersa short distance. formedon the stud, which is designed to t loosely in the large axial bore of the buffer- A collar 25D is 4c the c linder.

o5 tends loosely'f -T sleeve and to bear against the inner shoulder 2770i the steel buffer-sleeve when the striking end of the stud is projecting into the reciprocal path of the hammers far enough to receive 5' the full force of their blows. From the collar the stud extends. loosely and slidably into the adjacent end ofthe drill-holdingchuck. The striking-pin is, however, made a little larger in diameter than the drill-bit-holding aperxo ture in the chuck, and the inner end of thev chuck is provided with a counterbore to receive it, which is. made'enough longer than that portion of the striking-pin that extends into the chuck to allow it a short reciprocal r' 5 movement in it. The collar` ofthe strikingpin rests within the sleeve betweenv the shoulder 27 and the-ends of the hub of the steel buffer hub-rin and the thickness of the collar is arranged to eave. a space at the side ofthe zo collar for the collar tomove reciprocally in'a distance Sufficient to compensate for the variable and irregular feeding of the drill-bit forward into the rock relative to the speed it is cutting in'to the, rock and the driving-forward movement of the Striking-pin bv the blows of 'the hammer. The drill-holding chuck is provided with a toothed gear 34, which comprises a disk ortion that is referably formed integral wlth it intermediate :of 3o its ends. The gear rtion of the chuck is sitioned to extend om the end of the cylmder-bore 3 to and against 'the steel washer 3l.v To the end of the front cylinder 3 I secure a cylinder-head 35, preferably by means 3 5 of stud-screws36, which are threaded to the lugs 37 of the cylinder and extend loosely through lug ortions 38, formed on the cylinder-head. utsA 39 are threaded' to the end of the studs and clam the cylinder-head to This ont cylinder-head -is' provi ed with 'a hub portion 35, and the chuck extends beyond the gear tothe end of the hub. The chuck ear is not large enou h in diameter to the cylinder, and a hu 35B is formed on the inside of the cylinder-head, which surrounds the gear loosel and lls the space between it and the ,cylin erandextends toand against the steel washer, thus forming an abutment 'for all'fof v5e-the buffer-washers. -The front end of the cylinder-is provided with a depending lug 40, which is provided with an axlal aperture 41, in which a (gear 42 is rotatably mounted.- The rear en of the casing is also provided l with a depending lug 43, which contains an aperture 1n axial alinement with the aperture 41 in the lug 40 of the front end of the easing. Anut 44 is secured in the aperture ofthe lug 43, and' a feed-screw 45 isthreaded to the nut and 6e extends to and through the gear 42 loosely.

The front cylinder-head extends down over the depending lug and confines the ar in the lu and an aperture is formed in t e cylinderead, through which the ,feed-screw exe gear is provided with af used, and one of `the great advantages in 1- t of a drill-bit and drill-hol long sleeve or hub 42A, which extends from the gear loosely over the feed-screw to the nut. At its end portion it is provided in its inner peri heryr with two opgositely-arranged inverted ey-lugs 46, whic fit loosely and 7o slidably into two oppositely-arranged keg'- 'i Ways 47 formed on the opposite sides of t e feed-screw. The opposite end of the fe'edscrew is rotatably mounted in a block 48, which is supported by'a bracket 49, formed of two rearwardly-extending rods 49A and a cross-bar 50. This bracket-is secured to a shell 5I,which is provided at its opposite sides with guideways 52, and on the opposite sides 'of the bottom ofthe cylinders casing slide- Ways 53 fire formed, which fit slidably'in the guideways of the shell. The bottom of this supportin -shell is. rovided with a fan-tailed hub 54, w ich is a aptcd to be clamped by a' chuck of a suitable su qrrting-column. 8 5 The rock-cutting -bit 33 consists of aYY bar of any of the merchantable forms ,of cross-section of drill-bit tool-steel in use, it only being necessary to' make the axial aperture inr the drill-holding chuck of the same. .9o. form as the cross-section of the tool-steel used for the drill-bit. The shankend of the drill-hit is inserted in the aperture of the chuck loosely against the end ofthe strikingpin, and it may be provided with a collar or 95 with roject'lons positioned at apredetermin distance from its end and a ted to rest against the end of the chuck an to define the distance the shank shall extend vinto the'chuck and into drivi relation with the xo' a hamer-pistons, if desire in case the strik- 'ing-pin was dispensed with.' It is not "neces--V sary Vto use a collar or projections on the shank of the drill-bit when the striking-pin is 4r usingba striking-pin is that it enables me touse drillits as they are cut from the merchantable bars of tool-steel in-'their natural condition without machine or forge work of form-V ing a collar or projecting-lugs of an kind on 1 so their shank or striking ends and using 'Y with all work on th'em except what is neces-v sary, to form the rock-cutting on one end.

I. preferably use, however, lor Ythe drill-bit the cruciform drill-bit 'tool-steel in common 1 1.5 use -in rock-drilling e es, as shown in Fig. 13, andmake the a aperture in the drill holding chuck of cruciform shape in crosssection, as shown in Figi' 12, toi receive loosely the shank end of the drill-bit, which issimply inserted against the striking-pinand isheld 'from turning in the chuck b the introverted lips of the cruciform-shape a rture. This chuck and t e striking-'pin and the general features of the buier' mechanism and also the feedscrew rotation 'of the drill-bit form essential j features of and are ullyillustrated and described in my applications, Serial 'Nos 253,409, filed April 3, lees, and 213,988, filed 35 v cal paths of the two hammer-pistons, and it -St'ates Patent Office.

- pressed into it and (which is provided with a collar 54 on its front end, that is seated in a stepped counterbore 55 at the forward end'of the bore 3, in which the body of the chuck is placed. A counterbore 55A of larger diameter than the bore 3 and step 55 is formed in the outer end of the casing, and a gear 56 is revolubly seated init at the side of the chuck. This gear is provided with an axial aperture 57 of a polygonal form of cross-section, prefl erably a heXagon-shaped aperture, while the chuck is provided, preferably, with a round axial aperture 58. The front cylinder-head 35.A is secured to the end of the casing in a manner similar to that shown in the other arrangements of the drill. The gear 56 4meshes with the gear 42 and is rotated by the feed-screw in the same manner a's shown in Figs. 2 and 3. The drill-bit 59 is, however, provided with a round hammer-piston-striking shank end portion that projects loosely into and through the chuck into the reciprois also provided with a hexagon portion that extends loosely into the hexagon aperture in the gear, which ke sit so that it is rotated with the chuck. Tllis hexagon portion extends through the gear against the adjacent end of the chuck. The drill-bit is thus free to be inserted and withdrawninstantly by hand, as either the drill shown in the Figs. 2, e, 13,01: 14.

The operation of my multiple-hammer-piston motive-iluid-controlled rock-drilling engine is as follows: The rock-drillingengine is mounted on a supporting-column, with its rock-cutting drill-bit in operative relation to rock. The feed-screw is then rotated to feed the cylinder through its supportin -rshell until the cutting-points of the dril -bit lbear against the lrock and its shank end pushes against the end of the striking-pin, and it is held against the inner shoulder 27 of the steel buifer-sleeve and the striking end of the striking-pin in' the reciprocal path of the hammerpistons.' 1 The motive Huid, which is compressed air, is then turned on and flows through the ports, as aboveA described, c'ausing the hammer-pistons to reciprocate and strike against the striking-pin in successive alternate order, each hammer-pistonstriking on about one-half of the end of the strikingpin adjacent to it. The blows of the hammer-pistons against the strikingin are imparted against the end of the dril -bit, which is driven into the rock. The feed-screw is then rotated to feed the 4drill-cylinder and into rock, and at the same time the rotatory movement of the feed-screw through the gear 42, which is feathered to the feed-screw at the outer end of its hub portion, is rotated with the feed-screw, and its rotative movement is imparted to the chuck-gear and drillbit-holding chuck and through the medium of the imita-holdin Chuck to the drill-bit. Consequently while the drill-bit is being fed forward by the rotation of the feed-screw it is also being continuously rotated by the feedscrews rotative movement, and at the same time the two pistons are striking in alternate order with reat rapidity and in perfect unison and twice as fast as one haminer-piston would strike in a single-cylinder hammerpiston drill, and they are also each striking just as vhard and efiective drill-bit-driving blows against the striking-pin as one hammerpiston would strike in a single-cylinder drill.

While I have preferably illustrated and described the preferred construction and arran Yement of my multiple-hammer pistondril appliedto a duplex or twin hammer piston-drill, I do not wish to be limited to the exact arrangement and construction shown, as my invention ma be embodied in' struc'- tures differing in etail and arrangement -from that shown 'and as far as certain features are concerned is `applicable to rockdrilling engines operated by steam,electricity, or manual power.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1L A rock-drilling engine, comprisin a casacute angle to each other, a hammer-piston in each of said cylinders, mean's to secure a drill in the front end of said casing and means to reciprocate said hammer-pistons to deliver alternate blows upon said drill.

2,. A rock-drilling en ine, comprisin a casing containing two cy inders arrange at an in each of said cylinders, a drill-holding chuck in the front end of said casing, a striking-pin and means to maintain it in alinement with said chuck, and means to cause said hammer-pistons to deliver alternate blows'upon said pin. i

3. A rock-drilling `en ine, comprising a casing-containing two cy inders arranged at an acute angle to each other, a. hammer-piston chuck in the front end of said casing, a striking-pin and means to maintain it in alinel hammer-pistons. to ydeliver alternate blows 'drill-bit forward as fast as the drill-bit cuts acute angle to each other, a hammer-piston in each of said cylinders, a drill-holding ros,

ing containing two cylinders arrange at an ment with said chuck, means to cause said upon said pin, means Vto support said casing and means to simultaneously and rotate said chuck.

4. -In a rockdrilling engine, a. casing,

feed said casing means to support a drill in the front endV thereof, a pair of guideways in said casing converging toward the front end thereof, a

reciprocatory hammer mounted in each of said guideways and means to cause said hammers to deliver alternate blows uponv said drill.

5. In a rock-drilling en e, a drill-holder,

a gpair of hammers gui ed vto reciprocate reciprocate in said casing alon'g lines converging toward said chuck and means to cause said hammers to deliver alternate blows to a drill held in said chuck.

T. In a rock-drilling engine, a casing comprising twocylinders arranged at an acute l' angle to each other, a drill-chuck in the front end of said casing the axis of which bisects saidangle, a hammer-piston' in'each cylinder and means to convey a motive Huid to said pistons comprising ducts in said casing and grooves in said pistons, arranged so that said pistons are simultaneously reciprocated in opposite directions to deliver alternate blows to the drill in said chuck.

8. In a rock-drilling engine, a casing' comprising two cylinders arranged lat anacute angle to each other, a drill-chuck in the front en of said casing the axis of which bisects ,said angle, a lstrikmgin maintained in 4 tons, .arran .each o fsaid cylinders, l'gfive iiuld vto said casing to reciprocate saidA 6o' means tofeed said casing along sai axial alinement with sai chuck, a hammerpiston in each cylinder and means to convey `a motive fluid to said pistons comprising ducts in said casing and grooues in said pis edso;y that said pistons are sicmultaneous y.reci rocated in 'opposite directionsto deliver a ternate blows to the said striking-pin.

a rock-drilling engine, the combina tion o f a support, a .casing mounted thereon eompnsln two cylinders arr ed' at an acute ang e Yto each other, a dril -chuck rotatablyf'mounted in the'ront end of said cas-4 mg, a strllnng-pinfmaintained in axial alinement with sai,4 chuck, a hammer-piston in means to convey moanimer-pistons in opposite directions to delivgr alternate blows to saidstrikin -pin and support andto simultaneously rotate said chuck.-

1.0. In a rock-drilling engine, the combina- .tion of a casing containing 'a plurality of' cylinders, each having a hammeriston there-u in, said cylinders and pistons avin 'ducts formed .therein to convey a motive uid to simultaneously reciprocate said pistons in o posite directions, a drill-chuck arranged in tllie front end of said casing, a striking-pin re ciprocally mountedin said chuck, and buffer devices f or saidfpistons and striking-pin.

l1. In a rock-drilling engine, the combination of a casing containing -two cylinders, a hammer-piston in each cy inder, said casino' having ducts to convey motive Huid to sai( mg, a striking-pin .reciprocally mounted in sald chuck, b uii'er devlces for said pistons and striking-pin, a support `for said casing, a feed-screwto feed said casing along said support and intermeshing gears and feed-screw, whereby said chuck is rotated as said casing is fed.'

Q 12. In a Huid-controlled Vrock-drilling engine, a casing, two vcylinders in said-casing, each having -a halnineriston, a rotatable chuck in .said casing, a iiill arranged to .be `supported by said chuck, a striking-Din reciprocally supported in said c asing. and havmg one end projectlng into said chuck 1n operative strlkmg relation to said drill, a buffer surrounding said striking-pin and arranged pistons "and, said strikingin, a feed-screw for feedin said drill, an gears connected with said Ie said drill.

13. In a Huid-controlled rock-drilling A,engine, the combination With"the supportingshell and .the casing, having a pair of cylinders, each cylinder of'which is provided with from a source of supply arranged and adapted to reci opposite irections in alternate order, a steel buffer-sleeve in said cylinders slidablr different diameters and projectin at one end into the reciprocal path of said ammerpistons, a steel ring Aat the o posite end ,of said buffer-sleeve, having a ub that projects into the large bore of said sleeve, a space in said buffer-sleeve between the hub of said-ring andthe bottom of'the large'bore of said buil'er-sleeve, a rubber buffer-ringfat the'end oisaid hub-ring, a steel washer at .Ltending at one end .through said, steel fwa'sher, and Arubber buffer-ring, and hub# sleeve, to near the end of the hub of said hub,- ring, a drill in said chuck, a striking-pin ex.- tending in said steel buffer-sleeve and' into through the small bore of said steel uiferends extending into the large bore of'said pistons, a chuck in the front end of said cas-- to cushionl the spent blows of said hammer-- edscrew and chuck for rotating mounted therein and provided with a' bore of.

the end of said rubber buffer, a chuck eX-- sleeve into the reciprocal' path of said ham- -merpistons, and a collar intermediate of its on said chuck a hammer-piston, and fluid-ducts leading rocate said hammer-pistons in lIO ring, into the large bore of said steel buffer# end in said chuck, against said drill, a

Asaid striking-pin, a

resiliently cushion the movements of said buffer sleeve and ring, an abutment for said rubber buffer-ring, a feed-screw for feeding the drill, and means connected with said erell-screw and said chuck Jfor rotating said 1 y, 15. In a fluid-controlled piston-drill, the combination of acasing containing two cylinders, a piston reciprocably mounted in each cylinder, saidicasing having fluid-ducts steel buffer-sleeve, there being an operative drill-driving space in said steel buffer-sleeve between the collar and the adjacent end of the hub of said hub-ring, the opposite end of said striking-pin projecting slidably into said chuck in operative striking relation to said drill, a front cylinder-head secured to l the endof said cylinder, a hub-abutment portion extending to said steel washer, a feed-screw connected to said shell and casing and arranged to feed said drill, and means connected to said feed-screw and chuck for rotating said drill, substantially as described. 14. In a fluid-controlled hammer-piston4 drill, a casing, a chuck revolubly mounted in said casing, a drill in said chuck, two cylinders in said casing, having two pistons, arranged to reciprocate in opposite directions, and to drive said drill, a steel buHer-sleeve in saidv casing arranged to receive the spent x tatably mounted in the front end of said casing to hold a drill, a buffer-sleeve in said'casing in axial alinement with said chuck, a buffer-ring and washers surrounding said chuck at the end of said sleeve, and a striking-pin reciprocably supported by said sleeve and chuck to engage the end of a drill in said chuck and to receive the blows of said pistons and deliver them to the drill. blows of said hammer-pistons, a striking-pin slidably mounted at one end in said buffersleeve and slidably mounted at its opbposite uerring arranged to cushion the spent blows of rubber ring .arranged to in presence of two witnesses.

' 'JOHN GEORGE LEYNER. Witnesses:

R. L. BROWN,

GEORGEV R. GRIEVE.

In 4testimony whereof I affix my signature l leading from a source of supply, a chuck ro- 

